Improving Performance of LVRT Capability in Single-phase Grid-tied PV Inverters by a Model Predictive Controller

A Small-Scale Standalone Wind Energy Conversion System Featuring SCIG, CSI and a Novel Storage Integration Scheme

The maximum boost control (MBC) technique of voltage boosting offers the highest output voltage gain among other boost control techniques of Z -source inverter (ZSI). But, this technique suffers from the major drawback of sixth fundamental frequency (6thF1) ripple components of the impedance network inductor current. Due to this, the size/cost of the impedance network increases, which limits the practical applications of MBC. This article proposes an improved version of MBC via appropriate modification in the conventional space vector pulse width modulation of three-level ZSI (3L-ZSI). The improved MBC eliminates the problem of the 6thF1 impedance network inductor current ripple of 3L-ZSI without affecting its input/output gain and switching stress across power switches as compared to the existing MBC. Also, two new improved reduced common-mode voltage (RCMV) switching patterns have been proposed. As compared to the existing ones, the proposed RCMV switching patterns of 3L-ZSI offers reduced size of the impedance network while limiting the common-mode voltage magnitude to one-sixth of the available dc-link voltage. The above-mentioned findings have been successfully validated using theoretical analysis, simulation, and experimental results.

Improved Maximum Boost Control and Reduced Common-Mode Voltage Switching Patterns of Three-Level Z- Source Inverter

This paper proposes the use of advanced bus clamping switching sequences to reduce the impedance network inductor current ripple of the three-phase Z -source inverter (ZSI). Proposed technique is named as ABC4_MCB. MCB denotes that the maximum constant boost control method is used for the voltage boosting. One of the conventional space vector pulsewidth modulation of ZSI, “ZSVM6,” is termed as ZSVM6_MCB under the maximum constant boost control method. The switching sequences of ABC4_MCB technique are designed in such a way that it offers around 34% reduction in the maximum instantaneous inductor current ripple as compared to the ZSVM6_MCB for the equal average switching frequency. The factor of percentage reduction in the inductor current ripple using the proposed technique is constant over the entire range of shoot through duty ratio (0–0.48). Theoretical findings have been verified using simulation and experimental results.

A New SVPWM Technique to Reduce the Inductor Current Ripple of Three-Phase Z -Source Inverter

This article presents a new circuit topology for high voltage gain active switched boost quasi Z-source inverter (qZSI) and a pulsewidth modulation (PWM) technique. The higher boosting capability with a lower number of elements, the continuous source current, the less voltage stress across the devices, and having the common ground are the main advantages of the proposed structure. The voltage gain of the proposed inverter is twice that of the conventional capacitor-assisted qZSI (sCA-qZSI). Other benefits of the proposed inverter over the sCA-qZSI are the reduction of Z-source passive components and shoot-through current. Compared to the conventional active switched inductor boost qZSI, the proposed inverter has higher output voltage and also lower shoot-through current, while it has fewer components (one fewer inductor, two fewer diodes, but one more capacitor). The boost factor of the proposed inverter is more than twice that of the classic ones. Besides, a high gain PWM technique is proposed, which can be applied to any types of Z-source inverters. Both the simulation and experimental results of the proposed inverter under the proposed PWM technique are examined to validate their operation.

High Gain PWM Method and Active Switched Boost Z-Source Inverter With Less Voltage Stress on the Devices

Single phase transformerless wide range ac boost voltage regulator based on z-source network

Impedance (Z)-source inverter can provide stable output by smooth controlling of shoot-through duty cycle of any of the traditional PWM bridge inverters In this paper a control system for impedance-source inverter is designed suitable for wind power conversion system The main challenge in wind power system to maintain a constant voltage at the output with unpredictable variation in wind speed, is suitably taken care in steady state through buck-boost-capability of z-source inverter (ZSI) The shoot through state of ZSI is able to control and boost the output voltage when the wind generator voltage is not more enough to directly generate the desired output Again, the non-shoot through state can control and buck the output voltage when the wind generator voltage is more than desired So, the z-source PWM inverter replacing the conventional PWM inverter provides the unique output voltage regulation feature by making an appropriate choice of buck-boost factor The closed loop controller carefully monitors the wind generator voltage and controls the shoot-through and non-shoot through duty cycles automatically The whole system is simulated under arbitrary input variation condition and results are presented A comparison between the traditional and z-source inverter based system is also presented, which clearly indicates the benefits of the proposed system

Z-source inverter based control of wind power

Impedance (Z) source converters have been evolved as a new type of converter in addition to the two other existing converters; voltage source and current source converters. The new converter has many inherent advantages which can be used for many applications such as wind power conversion system, fuel cell and motor drive applications. Current research works focuses mainly on using Z-source network as a dc-link. The three phase ac-ac Z-source converter (TPZC) buck boost capabilities are verified to perform ac-ac conversion directly. Two different topologies of TPZC are compared in this paper. The boost ratio of improved topology is nearly 1.8 which is higher than 1.15 of traditional topology. Mathematical analysis of the proposed converters verified by MATLAB simulation results is presented.

Santosh Sonar

Papers

Improved Maximum Boost Control and Reduced Common-Mode Voltage Switching Patterns of Three-Level Z- Source Inverter

A New SVPWM Technique to Reduce the Inductor Current Ripple of Three-Phase Z -Source Inverter

Single phase transformerless wide range ac boost voltage regulator based on z-source network

Z-source inverter based control of wind power

Comparative analysis of three phase ac-ac Z-source converter topologies